Merge remote-tracking branch 'linus/master' into staging/for_v3.8

* linus/master: (1428 commits)
  futex: avoid wake_futex() for a PI futex_q
  watchdog: using u64 in get_sample_period()
  writeback: put unused inodes to LRU after writeback completion
  mm: vmscan: check for fatal signals iff the process was throttled
  Revert "mm: remove __GFP_NO_KSWAPD"
  proc: check vma->vm_file before dereferencing
  UAPI: strip the _UAPI prefix from header guards during header installation
  include/linux/bug.h: fix sparse warning related to BUILD_BUG_ON_INVALID
  Linux 3.7-rc7
  powerpc/eeh: Do not invalidate PE properly
  ALSA: hda - Fix build without CONFIG_PM
  of/address: sparc: Declare of_iomap as an extern function for sparc again
  PM / QoS: fix wrong error-checking condition
  bnx2x: remove redundant warning log
  vxlan: fix command usage in its doc
  8139cp: revert "set ring address before enabling receiver"
  MPI: Fix compilation on MIPS with GCC 4.4 and newer
  MIPS: Fix crash that occurs when function tracing is enabled
  MIPS: Merge overlapping bootmem ranges
  jbd: Fix lock ordering bug in journal_unmap_buffer()
  ...

1 files changed, 15 insertions, 4 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 01e944a017a4..4da797fa5ec5 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -138,6 +138,8 @@ static int netlink_dump(struct sock *sk);
 static DEFINE_RWLOCK(nl_table_lock);
 static atomic_t nl_table_users = ATOMIC_INIT(0);
 
+#define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
+
 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
 
 static inline u32 netlink_group_mask(u32 group)
@@ -345,6 +347,11 @@ netlink_update_listeners(struct sock *sk)
 	struct hlist_node *node;
 	unsigned long mask;
 	unsigned int i;
+	struct listeners *listeners;
+
+	listeners = nl_deref_protected(tbl->listeners);
+	if (!listeners)
+		return;
 
 	for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
 		mask = 0;
@@ -352,7 +359,7 @@ netlink_update_listeners(struct sock *sk)
 			if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
 				mask |= nlk_sk(sk)->groups[i];
 		}
-		tbl->listeners->masks[i] = mask;
+		listeners->masks[i] = mask;
 	}
 	/* this function is only called with the netlink table "grabbed", which
 	 * makes sure updates are visible before bind or setsockopt return. */
@@ -536,7 +543,11 @@ static int netlink_release(struct socket *sock)
 	if (netlink_is_kernel(sk)) {
 		BUG_ON(nl_table[sk->sk_protocol].registered == 0);
 		if (--nl_table[sk->sk_protocol].registered == 0) {
-			kfree(nl_table[sk->sk_protocol].listeners);
+			struct listeners *old;
+
+			old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
+			RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
+			kfree_rcu(old, rcu);
 			nl_table[sk->sk_protocol].module = NULL;
 			nl_table[sk->sk_protocol].bind = NULL;
 			nl_table[sk->sk_protocol].flags = 0;
@@ -982,7 +993,7 @@ int netlink_has_listeners(struct sock *sk, unsigned int group)
 	rcu_read_lock();
 	listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
 
-	if (group - 1 < nl_table[sk->sk_protocol].groups)
+	if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
 		res = test_bit(group - 1, listeners->masks);
 
 	rcu_read_unlock();
@@ -1625,7 +1636,7 @@ int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
 		new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
 		if (!new)
 			return -ENOMEM;
-		old = rcu_dereference_protected(tbl->listeners, 1);
+		old = nl_deref_protected(tbl->listeners);
 		memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
 		rcu_assign_pointer(tbl->listeners, new);